Melt 2 tbsp. of the butter in a large saute pan and saute the leeks until tender. Add garlic and mushrooms and saute until mushrooms release their juices and are softened. Remove from heat and set aside.

Melt 2 tbsp. of the butter in a medium saucepan then add the flour, whisking until smooth. Add the broth and tomato paste and continue to whisk until mixture is hot and thickened; stir in the sour cream and continue to cook just until heated through.

Melt remaining butter in a large skillet and quickly saute the bison. Combine all ingredients and spoon atop hot, cooked noodles.

Chef's NotesAbout. . .Bison meat is surprisingly tender, with a taste resembling beef. It is extremely lean, so use caution and do not overcook.